<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>姓名案例计算属性简写</title>
    <script src="../js/vue.js"></script>
</head>

<body>
    <div id="root">
        姓：<input type="text" v-model:value=" firstName"><br><br>
        名：<input type="text" v-model:value="lastName"><br><br>
        全名：<span>{{fullName}}</span>
    </div>
</body>
<script>
    Vue.config.productionTip = false;
    new Vue({
        el: '#root',
        data: {
            firstName: '张',
            lastName: '三',
            fullName:'张三'
        },
        watch:{
            firstName(newValue){
                this.fullName = newValue + '_'+this.lastName
            },
            lastName(newValue){
                this.fullName = this.firstName+'_'+newValue
            }
        }
    })
</script>

</html>